BitPumpPlain: TiffEntry: don't load type into enum first.
BitPumpPlain: TiffEntry: don't load type into enum first.

Fixes following complaints:
/home/lebedevri/darktable/src/external/rawspeed/RawSpeed/TiffEntryBE.cpp:39:7:
runtime error: load of value 26624, which is not a valid value for type
'TiffDataType'
/home/lebedevri/darktable/src/external/rawspeed/RawSpeed/TiffEntryBE.cpp:40:78:
runtime error: load of value 26624, which is not a valid value for type
'TiffDataType'

LebedevRI/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,klauspost/rawspeed,darktable-org/rawspeed,anarsoul/rawspeed,darktable-org/rawspeed,klauspost/rawspeed,anarsoul/rawspeed,anarsoul/rawspeed